The present invention relates to an improved dust collection and filter system for use in a mobile debris collection machine such as that manufactured by Tennant Company of Minneapolis, Minn. and sold under the trademark xe2x80x9cLitter Hawk.xe2x80x9d It is important in mobile debris and dust collection machines to provide a filter system which will remove dust from the air stream before it is discharged into the atmosphere. Normally, debris collection machines will use a high volume of air flow as this is necessary to insure adequate dust and debris pickup. It is important that the air discharged from the machine be as dust-free as possible. Concurrent with the problem of removing dust is to provide a filter system which is sufficiently adequate that it does not require constant maintenance and removal of filter elements for cleaning. Further, any dust collection system which will easily clog will create a back pressure which can adversely affect vacuum performance and thus litter pickup.
The present invention is addressed to the above-described problems and specifically functions with a two-stage dust and debris separation system which insures that the high volume of air flow will be adequately filtered before discharge and that the filter system will remain unclogged for a substantial period of machine use. The system includes a first filter stage which is formed by a rotating perforated plate attached to the vacuum fan of the air flow system and which separates debris and a high percentage of the dust from the dust and debris collected at the machine inlet. The air flow from the vacuum fan is divided into two parallel paths, each having a second stage filter formed of a pair of pleated filter elements joined at the top and separated at the bottom.
The present invention relates to an improved filter system for a debris collection machine.
A primary purpose of the invention is to provide a filter system which comprises multiple filter stages, with the last filter stage including parallel air flow paths, each of which terminates in pleated filter elements.
Another purpose of the invention is to provide an improved filter system in which the first stage comprises a perforated plate, rotatable with the vacuum fan, and separating debris from the air flow and with the second filter stage comprising parallel air flow paths, each of which terminates in pleated filter elements.
Another purpose of the invention is to provide an improved filter system in which there is a deflector located adjacent the vacuum fan and first filter stage to direct dust and debris in the direction of rotation of these elements to spin the debris into the collecting canister to assist in compacting the debris therein.
Another purpose of the invention is to provide a filter system as described including a pulsed water spray positioned to direct water across the first stage filter element.
Another purpose is to provide a filter system as described in which each of the outlets of the second filter stages have air diffusers in the form of screens to disperse and direct the outlet air so that it does not disturb debris lying outside or along the swept path.
Another purpose is to provide a mobile debris collection machine as described with an improved filter system and with a debris canister which may have an over-center linkage to facilitate release and removal of debris from the collection canister.
Other purposes will appear in the ensuing specification, drawings and claims.